The present invention relates to a bearing plate for supporting a portion of a mine roof.
When earth is dug away to form a tunnel in a mine, the earth on the upperside of the tunnel forms a roof of the mine. If this earth is not supported, it may collapse. Accordingly, it has been a common practice to use bearing plates to support the roof of a mine. Typical bearing plates are disclosed in U.S. Pat. Nos. 4,037,418 and 4,371,293. These bearing plates are pressed against the roof of the mine by bolts which extend into holes drilled in the roof of the mine.
Although it has been suggested that mine roof bearing plates could be cast in the manner shown in U.S. Pat. No. 3,226,934, mine roof bearing plates are more commonly stamped from sheet metal. In order to increase the rigidity of these sheet metal mine roof bearing plates, they have been formed with longitudinally extending ribs which increase the section modulus of the bearing plates. However, even though ribs are formed in the bearing plates, it may be necessary to form then of relatively thick sheet metal to withstand the loads applied to them by the roof of the mine.